APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: John Chisholm (UT Austin)
Title: A Glimpse Below the Lyman Limit: New observational advances on the escape of ionizing photons from local galaxies
Date (JST): Thu, Oct 15, 2020, 10:00 - 11:00
Place: Zoom
Abstract: The neutral gas between galaxies was rapidly reionized at redshifts between 6-10. The origin of these ionizing photons remains elusive, but fundamentally shapes the subsequent evolution of the galaxies and the formation of large-scale structure in the universe. The key to unraveling the epoch of reionization is an understanding of both the sources emit ionizing photons (stars vs. active galactic nuclei) and how these ionizing photons escape galaxies. I will present an overview of the recent observational advances that have led to the discovery of local star-forming galaxies that emit ionizing photons, including a recent large Hubble Space Telescope survey that has more than doubled the known number of emitters of ionizing photons. A statistical sample allows for the first detailed look into what types of star-forming galaxies emit ionizing photons and how those ionizing photons can escape star-forming galaxies. I will focus on new probes from the rest-frame ultraviolet that promise to diagnose the porosity of the neutral medium within galaxies at high-redshift. These local surveys set the stage for upcoming telescopes to determine the impact of star-forming galaxies on Cosmic Reionization.